To land on a runway and reuse more of the craft.
But are at the mercy of the wind and require a water landing and recovery - and you can't just lift a 727-sized object out of the water and drop it onto an aircraft carrier with a helicopter.
Extremely, but they could be gotten rid of if the system were completely redesigned.
for the shuttle itself, it simply isn't possible. It would require a completely different vehicle.
Well, no, the restrictions are quite similar to the restrictions on earlier capsules. There is
some complex aerodyanamics and thermodynamics at work there.